Don't forget the Andorians and Aenar, weren't they two races of the same species?

More like two distinct subspecies, akin to modern humans and Neanderthals. Aenar had larger, higher-crowned skulls, differently shaped antenna tips, and telepathic abilities, in addition to being blind and albino.

Now we're getting into the problem of race being a cultural construct, but physical differences are part of what defines a race, so it's unclear to me whether there's a real difference between a race and a sub-species (and I'd call Neanderthals a different species altogether.)